ABSTRACT Thermal lens spectrometry has been used for the determination of iron in calf serum. The method is based on dissociation of Fe3+ from proteins, reduction of Fe3+ to Fe2+ and formation of a coloured complex between Fe2+ and bathophenanthroline. Contrary to the spectrophotometric method, it is shown that thermal lens spectrometry is less sensitive to scattering caused by the presence of small particles remaining in the test solution after the deproteinization step. The background signal is very small and the response is only slightly dependent on the amount of scattering particles. The method is reliable, sensitive and reproducible. The limit of detection for iron is 4 ppb and the relative standard deviation is around 2%. It is expected that the volume of serum sample necessary for an analysis can be reduced to less than 100 μl. 相似文献
根据折叠桌的运动特征,选取折叠桌的四分之一为研究对象,建立任意角度下桌脚点的运动变化模型。考虑到产品稳固性、加工便利性和节约用材三方面对加工参数的影响,对折叠桌进行受力分析,得到多目标组合优化模型,用以确定出折叠桌的最优设计参数。针对用户提出的桌面形状要求,建立桌脚曲线的参数方程。作为模型推广,以椭圆状折叠桌为例,运用Matlab画出了桌脚边缘线在折叠过程中的动态变化示意图。同时,又深入研究Robert van Embricqs的滑动折叠桌,建立了新的桌脚曲线参数方程。最后,运用Matlab对多种形状折叠桌进行仿真,编写多目标优化算法,得出了最优加工参数,并进行了算法描述。 相似文献
Conventional optics is diffraction limited due to the cutoff of spatial frequency components, and evanescent waves allow subdiffraction optics at the cost of complex near‐field manipulation. Recently, optical superoscillatory phenomena were employed to realize superresolution lenses in the far field, but suffering from very narrow working wavelength band due to the fragility of the superoscillatory light field. Here, an ultrabroadband superoscillatory lens (UBSOL) is proposed and realized by utilizing the metasurface‐assisted law of refraction and reflection in arrayed nanorectangular apertures with variant orientations. The ultrabroadband feature mainly arises from the nearly dispersionless phase profile of transmitted light through the UBSOL for opposite circulation polarization with respect to the incident light. It is demonstrated in experiments that subdiffraction light focusing behavior holds well with nearly unchanged focal patterns for wavelengths spanning across visible and near‐infrared light. This method is believed to find promising applications in superresolution microscopes or telescopes, high‐density optical data storage, etc.
The higher wear resistance of Ni based nano composite coatings makes them potential replacement in protecting the substrate materials. The role of surface roughness of the coating along with wear parameters on the specific wear rate, pin temperature, and COF are addressed in the present study. The use of hard nano Al2O3 particles found significant role in increasing the resistance to wear for Ni matrix coatings on Al6061 material. The resistance to dislocation offered by these nano Al2O3 particles and smear out of debris with plastic deformation indicated abrasive and adhesive nature of wear mechanism in combination. The optimization of wear parameters are carried out by surface response method based grey relation analysis. The normal load applied onto the pin has significant influence on the specific wear rate and temperature rise in the pin. The surface roughness of the coating has also found instrumental in the higher pin temperature and friction coefficient. 相似文献